Circuit breaker



June F. G. VON HOORN 08 CIRCUIT BREAKER Filed June 25; 19415 Inventor:

Fred G. von Hoor'n,

10, w my! His Abtor'ne Patented Jim. 17, 1941 Fred G. von Boom,Bridgeport, Conm,

Electric Company, a corporation of New General York usignor toApplication June 25. 1943, Serial No. 492.284

' 3 Claims. (01. 201-48) My invention relates to circuit breakers, moreparticularly to manually operated current responsive circuit breakers,and has for its object a simple and reliable circuit breaker providedwith means for holding the circuit breaker closed by means of a handlein .the event of an overload, together with external means forcalibrating the current responsive tripping device and a seal around thehandle of the circuit breaker.

In carrying out my invention in one form I provide a pivoted arm on thesupporting framework of thecircuit breaker which cooperates with thehandle and with the normally secured tripping member of the circuitbreaker in such manner that, if the handle is held in a predeterminedextreme circuit closing position, the current responsively held trippingmember is held by the handle to prevent opening of the circuit breaker,

I also provide an electric shunt for the current responsive device,which shunt is secured to the circuit breaker on the exterior of thecasing so that it may be readily removed and changed to effect thecalibration of the circult'breaker.

To effect a seal around the handle, I mount the handle for springpressed engagement with a wall of the enclosing casing.

For a more complete understanding of my invention, reference should behad to the accompanying drawing, Fig. 1 of which is a side elevationview mainly in section of a circuit br'eaker provided with my invention;Fig. 2 is a fragmentary sectional view taken along the line 2-2 of Fig.1 looking in the direction of the arrows;

while Fig. 3 is a fragmentary view of a part of the device.

In carrying out my invention in one form I provide a spring contact armIii mounted on a pivot ll between two upright sides of a supportingframework i2, only one side of which is shown. The arm comprises a rigidportion pivoted on the pivot H and provided with a stop projection l3and an operating projection It. This member has secured to its lowerend, as by rivets ll, the spring arm ill on the end of which is secureda movable contact l1 cooperating with a stationary contact is.

As shown, the breaker is held in its closed circuit position by means ofa toggle consisting of two links II and 23, the lower end of the link 23being pivotally connected by a pivot 2i to the operating projection ll,while the upper'end of the link I3 is connected by pivot 22 to theintermediate point of a normally fixed trip arm 23. This toggle isbroken to open the circuit position shown in the breaker by moving ahandle 24 toward the left hand, as seen in the drawing, the handle beingmounted on an inverte U-shaped operating member, only one arm 23 ofwhich is seen, which embraces the supporting framework i2 and has theends of its arms pivoted on lateral projections 23 secured to theframework. A pair of helical tension springs 21, only one of which isshown, are provided on opposite sides of the toggle. Each spring has oneend connected to the movable pivot 23 of the toggle and its other upperend connected to. the handle 24. Thus when the handle is moved on itspivot 23 toward the left until the center line of the spring 21 is tothe left of the pivot 22, the spring snaps the pivot 28 toward the leftthereby opening the circuit breaker. In its open position the projectioni3 rests against a stop pin 23.

Normally the left-hand end 33 of the arm 23 is secured by engagementwith the end of a screw 3| carried by a thermostat 32, whereby the arm23 is held against movement in a clockwise direction about its pivot 32aby the force applied by the spring 21. Upon the occurrence of apredetermined maximum current, however, the upper end of the thermostat32 moves toward the left far enough to release the arm 23 whichthereupon moves clockwise about its pivot.and effects themovement of theswitch arm to an open circuit position. 7 r

In order that the arm 23 may be held in the drawing, even though. it hasbeen released by the thermostat, I have provided a lever 33 forming aconnecting member mounted on the fixed pivot 32a. The lower end of thislever engages the operating arm 25 carrying the handle, while its upperend engages an upright portion 34 of the trip arm 23. Actually this arm33 is provided in two parts which are duplicated on each side of thesupporting framework, there being another arm 33 (not shown) on theoppo- I site side of the framework mounted also on the pivot 32a. Theupper ends of these arms are connected together by a. cross rod 33,which rod is the part engaging the vertically extending portion 34 onthe arm 23.

' The lever 33 furthermore is so arranged that when the arm 23 is in itsnormal secured position, as shown in the drawing, the lower end of thelever 33 pushes the arm 25' and with it the handle 24 slightly in acounterclockwise direction about the pivot 28 so that the arm is inappreciable spaced relation from the stop 33. It will be observed thatthe the helical spring 21, but since it is acting. almost forces areapplied entirely byw directly on the arm 23, its force applied to thearm 23 overpowers the relatively small amount of its force which opposesmovement of the handle toward the left hand. Therefore, the handle ismoved slightly away from stop 33.

However, if it is desired to hold the circuit breaker in its closedcircuit position, this can be done by moving the handl 24 toward theright hand until the arm 25 comes to rest against the stop 35. Thismoves the arm 33 through a small angle in a counterclockwise directionabout the pivot 32a, whereby the cross bar 35 by engagement with the arm23 moves the arm slightly in a counterclockwise direction about thepivot 32a. As long as the handle is held in this position, the arm issecured, regardless of the position of the screw 39. As a matter offact, if the handle 26 is held firmly in th exact position shown in thedrawing, the arm 23 will be held against movement when released by thethermostat. However, movement of the handle toward the right intoengagement with the stop 36 assures that the contact arm will be heldagainst openingmovement.

The latching end 33 of the 23 is preferably a metal part which issecured to the end of the arm between layers Of insulation so as to beelectrically insulated from the arm 23,

The mechanism, as shown, is enclosed in acasing or housing 3? made of amolded electrically insulating material, at the bottom of which thesupporting framework. 52 secured. Electrical comiections are with thecircuit breaker by means of two connectors or conductors 38 and 39mounted in the lower wall of the casing and extending through thecasing. The conductor 38 also serves as a support for the thermostat 32whose lower end is electrically and mechanically connected, as by ariveted and brazed joint 40, to a. strap member 4i secured on theconductor by a. nut 42 inside the casing. In a somewhat similar manner,the stationary contact I8 is mounted on a conducting strap 43 secured tothe conductor 39 by a nut 45.

The circuit through the circuit breaker between the external connectors38 and 39 may be traced from the connector 38 through the thermostat 32to its upper end and then through a flexible conductor 45 to a secondarylllg or connector 46 mounted in the bottom wall of the casing. A secondshunt circuit of adjustable resistance is provided by a strap conductor41 which extends directly on the exterior of the casing from theconductor 38 to the conductor 46. From the conductor 46 a flexibleconductor 48 leads to the end of the contact arm, and the circuit thenleads through the two contacts and the conductor 39 to the exterior ofthe circuit breaker.

Calibration or change in the tripping current value is effected veryconveniently from the exterior of the casing by interchanging the shuntconductor 47 for one having a suitable electrical resistance. The shuntconductor is provided with an aperture at each end, through whichapertures the conductors 38 and 46 extend. Thus, to remove the shunt thenuts 49 and 50 are removed from the conductor 38 and the nut 5| isremoved from the conductor 46. The shunt can then be slipped off theconductors and the desired one put in place and then secured by turningthe nuts 50 and 5| tightly down against it so as to form a goodmechanical, and also good electrical, connection at each end between theshunt and the conductors themselves. The outer nut 49 on the conductor33 is the usual clamping nut for eflecting an electrlcal connection withan external circuit.

adjustment of the current response of the thermostat, or rather oi theamount of deflection required of the thermostat to release the arm 23,can be effected by adjustment of the crew 3|. It is contemplated,however, that this screw will be given a standard adjustment when thebreaker is assembled, and thereafter calibration of the thermostat totrip open the breaker in response to a. desired current through thecontacts will be effected by applying a suitable shunt 41. The shunts,for example, may be constructed with resistance values to givepredetermined circuit breaker current ratings and stamped with thosevalues, such as 50, and amperes. It will be understood that any currentvalue above the particular current value for which the breaker iscalibrated will cause heating of the thermostat and distortion of itsuiiicient to open the circuit breaker, provided the circuit breaker isnot held closed manually by means of the handle 24, as previouslydescribed.

Another feature of the circuit breaker is a. dusttight and substantiallyairand liquid-tight seal provided between the handle 24 and the sides ofthe aperture of the casing through which the handle extends. To providefor this seal, the handle is provided with an arcuate portion 52extending in the direction of its motion, this arcuate portion havingfor its center the pivot of the handle on the projection 26. By means ofa compression spring 54 the handle is forced outward with the arcuateportion resting against and overlapping the complementary inner wall ofthe casing on each side of the aperture. Also, as shown in Fig. 2, thearcuate portion 52 with the handle secured at approximately its middle,is provided with ridges and grooves extending in the direction ofmovement of the handle which fit closely with complementary grooves andridges in the upper surface of the casing. Thus, as shown in Fig. 2, thehandle is provided with a ridge 55 and groove 56 on each side of theaperture through which the handle extends.

To facilitate this mounting of the handle on the inverted U-shaped metaloperating member of which the arm 25 is a part, radially extendingprojections 51 and 58 are provided on this member which cooperate withrecesses in the handle. Thus the handle is free to move radially outwardin accordance with the force applied by the spring 54.

A second stop 53 limits the movement of the arm 25 in a counterclockwisedirection, and a stop 60 is provided on the frame, against which the endof the contact arm comes to rest in the open circuit position.

When the arm 23 is moved clockwise on overload to open the circuitbreaker, it can be brought back with its end 30 in latching engagementwith the screw 3| by means of the handle, assuming that the thermostatis allowed to cool and bring the screw back into latching position. Toeffect this, the handle may be moved in either direction.

When the trip arm 23 is released by the thermostat, the spring 21 causesit to move clockwise about its pivot 32. At the same time the trip arm,by engagement with the cross rod 35, moves the lever 33 clockwise sothat the lever 33 in turn moves the operating arm 25 counterclockwiseabout its pivot 26. This movement of the operating member 25 carries theupper end of the spring 21 toward the pivot 22, the pivot and the springmoving toward each other. When the pivot reaches a position to the rightof the center line of the spring, the spring snaps the toggle to itsbroken position thereby opening the circuit breaker. During this openingmovement, the spring biases the handle toward the left to a centralposition in which a projection 6| on the operating member 25 restsagainst a stop projection 62 (Fig. 3) on the trip arm 23. The trip arm23 is brought to rest by the engagement of the cross rod 35 with theprojection 53 on the frame.

If the handle 24 after this automatic opening is moved toward the left,the engagement of the projection 6| with the projection 62 on the triparm 23 effects counterclockwise movement of the arm until its left-handend is moved downward to its latching position. On th othe hand, if thehandle is moved toward the right hand'from this central position, itsengagement with the lever 33 causes this lever to reset the lever 23while at the same time the circuit breaker is closed.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I therefore contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The combination in a circuit breaker provided with an enclosingcasing made of insulating material and with switch contacts, operatingmechanism therefor, and current responsive tripping means for saidcontacts inside said casing, of first and second conductors mounted in awall of said casing and extending therthrough for the externalconnection of said circuit breaker in a predetermined circuit, anintermediate conductor mounted in a wall of said casing and extendingtherethrough, electric connections inside said casing including saidcurrent responsive means between said first conductor and saidintermediateconductor, a current calibrated shunt conductor on theexterior of said casing electrically connected between said firstconductor and said intermediate conductor, and an electric connectioninside said casing from said intermediate conductor through saidcontacts to said second conductor.

2. The combination in a circuit breaker provided with an enclosingcasing made of insulating material and with switch contacts, operatingmechanism therefor, and a bimetallic thermostat for tripping saidcontacts mounted inside said casing, of means for effecting a,predetermined standard adjustment of said thermostat for all currentvalues at which said first and second conductors mounted in a wall ofsaid casing and extending therethrough for the external connection ofsaid circuit breaker in a contacts are tripped,

predetermined circuit, an intermediate conductor mounted in a wall ofsaid casing and extending therethrough, electric connections inside saidcasing including said thermostat between said first conductor and saidintermediate conductor, a shunt conductor on the exterior of said casingelectrically connected between said first conductor and saidintermediate conductor for determining the final current tripping valueof said thermostat, and an electric connection inside said casing fromsaid intermediate conductor through said contacts to said secondconductor. 9

3. The combination in a circuit breaker provided with an enclosingcasing made of insulating material and with switch contacts,manuallyoperated operating mechanism therefor, and a bimetallic barthermostat for normally holding said operating mechanism to maintainsaid contacts in engagement with each other after they have been movedinto engagement by said manual operating means, of adjustable holdingmeans for said operating mechanism on the movable end of saidthermostat, said holding means having a predetermined standardadjustment for all contact current tripping values of said thermostat,of first and second conductors mounted in a wall of said casing andextending therethrough for the external connection of said circuitbreaker in a predetermined circuit, an intermediate conductor mounted ina wall of said casing and extending therethrough, electric connectionsinside said casing including said thermostat between said' firstconductor and said intermediate conductor, a shunt conductor on theexterior of said casin electrically connected between said firstconductor and said intermediate conductor, and an electric connectioninside said casing from said intermediate conductor through saidcontacts to said second conductor, said shunt conductor shunting aroundsaid thermostat a predetermined amount of the current passing throughsaid contacts thereby to fix the value of the current through saidcontacts effecting separation of said contacts by said thermostatindependently of said standard adjustment or said holdinfl means.

FRED G. von HOORN.

REFERENCES CITED The following references are of record in the

